That might be so, but I don't think so. Remember - this isn't emulation but on-the-fly cross-compile. And the OS and all Apple apps will be native ARM code. I remember that, during the PPC > x86 transition, Rosetta apps were a bit slower but not unacceptably so. In my mind, the biggest issue is the UI. You would need a precise pointing device, such as a trackpad or mouse, rather than relying purely on touch. The targets are just too small for fingers to work well.